Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

Descriptions and uses for these constants are described within the curl_setopt(), curl_multi_setopt() and curl_getinfo() documentation.

CURLOPT_AUTOREFERER (integer): Available since PHP 5.1.0
CURLOPT_COOKIESESSION (integer): Available since PHP 5.1.0
CURLOPT_DNS_USE_GLOBAL_CACHE (integer)
CURLOPT_DNS_CACHE_TIMEOUT (integer)
CURLOPT_FTP_SSL (integer): Available since PHP 5.2.0
CURLFTPSSL_TRY (integer): Available since PHP 5.2.0
CURLFTPSSL_ALL (integer): Available since PHP 5.2.0
CURLFTPSSL_CONTROL (integer): Available since PHP 5.2.0
CURLFTPSSL_NONE (integer): Available since PHP 5.2.0
CURLOPT_PRIVATE (integer): Available since PHP 5.2.4
CURLOPT_FTPSSLAUTH (integer): Available since PHP 5.1.0
CURLOPT_PORT (integer)
CURLOPT_FILE (integer)
CURLOPT_INFILE (integer)
CURLOPT_INFILESIZE (integer)
CURLOPT_URL (integer)
CURLOPT_PROXY (integer)
CURLOPT_VERBOSE (integer)
CURLOPT_HEADER (integer)
CURLOPT_HTTPHEADER (integer)
CURLOPT_NOPROGRESS (integer)
CURLOPT_NOBODY (integer)
CURLOPT_FAILONERROR (integer)
CURLOPT_UPLOAD (integer)
CURLOPT_POST (integer)
CURLOPT_FTPLISTONLY (integer)
CURLOPT_FTPAPPEND (integer)
CURLOPT_FTP_CREATE_MISSING_DIRS (integer)
CURLOPT_NETRC (integer)
CURLOPT_FOLLOWLOCATION (integer): This constant is not available when open_basedir or safe_mode are enabled.
CURLOPT_FTPASCII (integer)
CURLOPT_PUT (integer)
CURLOPT_MUTE (integer)
CURLOPT_USERPWD (integer)
CURLOPT_PROXYUSERPWD (integer)
CURLOPT_RANGE (integer)
CURLOPT_TIMEOUT (integer)
CURLOPT_TIMEOUT_MS (integer)
CURLOPT_TCP_NODELAY (integer): Available since PHP 5.2.1
CURLOPT_POSTFIELDS (integer)
CURLOPT_PROGRESSFUNCTION (integer): Available since PHP 5.3.0
CURLOPT_REFERER (integer)
CURLOPT_USERAGENT (integer)
CURLOPT_FTPPORT (integer)
CURLOPT_FTP_USE_EPSV (integer)
CURLOPT_LOW_SPEED_LIMIT (integer)
CURLOPT_LOW_SPEED_TIME (integer)
CURLOPT_RESUME_FROM (integer)
CURLOPT_COOKIE (integer)
CURLOPT_SSLCERT (integer)
CURLOPT_SSLCERTPASSWD (integer)
CURLOPT_WRITEHEADER (integer)
CURLOPT_SSL_VERIFYHOST (integer)
CURLOPT_COOKIEFILE (integer)
CURLOPT_SSLVERSION (integer)
CURL_SSLVERSION_DEFAULT (integer)
CURL_SSLVERSION_TLSv1 (integer)
CURL_SSLVERSION_SSLv2 (integer)
CURL_SSLVERSION_SSLv3 (integer)
CURL_SSLVERSION_TLSv1_0 (integer): Available since PHP 5.5.19 and 5.6.3
CURL_SSLVERSION_TLSv1_1 (integer): Available since PHP 5.5.19 and 5.6.3
CURL_SSLVERSION_TLSv1_2 (integer): Available since PHP 5.5.19 and 5.6.3
CURLOPT_TIMECONDITION (integer)
CURLOPT_TIMEVALUE (integer)
CURLOPT_CUSTOMREQUEST (integer)
CURLOPT_STDERR (integer)
CURLOPT_TRANSFERTEXT (integer)
CURLOPT_RETURNTRANSFER (integer)
CURLOPT_QUOTE (integer)
CURLOPT_POSTQUOTE (integer)
CURLOPT_INTERFACE (integer)
CURLOPT_KRB4LEVEL (integer)
CURLOPT_HTTPPROXYTUNNEL (integer)
CURLOPT_FILETIME (integer)
CURLOPT_WRITEFUNCTION (integer)
CURLOPT_READFUNCTION (integer)
CURLOPT_PASSWDFUNCTION (integer)
CURLOPT_HEADERFUNCTION (integer)
CURLOPT_MAXREDIRS (integer)
CURLOPT_MAXCONNECTS (integer)
CURLOPT_CLOSEPOLICY (integer): Removed in PHP 5.6.0.
CURLOPT_FRESH_CONNECT (integer)
CURLOPT_FORBID_REUSE (integer)
CURLOPT_RANDOM_FILE (integer)
CURLOPT_EGDSOCKET (integer)
CURLOPT_CONNECTTIMEOUT (integer)
CURLOPT_CONNECTTIMEOUT_MS (integer)
CURLOPT_SSL_VERIFYPEER (integer)
CURLOPT_CAINFO (integer)
CURLOPT_CAPATH (integer)
CURLOPT_COOKIEJAR (integer)
CURLOPT_SSL_CIPHER_LIST (integer)
CURLOPT_BINARYTRANSFER (integer)
CURLOPT_NOSIGNAL (integer)
CURLOPT_PROXYTYPE (integer): Available as of cURL 7.10.
CURLOPT_BUFFERSIZE (integer)
CURLOPT_HTTPGET (integer)
CURLOPT_HTTP_VERSION (integer)
CURLOPT_SSLKEY (integer)
CURLOPT_SSLKEYTYPE (integer)
CURLOPT_SSLKEYPASSWD (integer)
CURLOPT_SSLENGINE (integer)
CURLOPT_SSLENGINE_DEFAULT (integer)
CURLOPT_SSLCERTTYPE (integer)
CURLOPT_CRLF (integer)
CURLOPT_ENCODING (integer)
CURLOPT_PROXYPORT (integer)
CURLOPT_UNRESTRICTED_AUTH (integer)
CURLOPT_FTP_USE_EPRT (integer)
CURLOPT_HTTP200ALIASES (integer)
CURLOPT_HTTPAUTH (integer)
CURLAUTH_BASIC (integer)
CURLAUTH_DIGEST (integer)
CURLAUTH_GSSNEGOTIATE (integer)
CURLAUTH_NTLM (integer)
CURLAUTH_ANY (integer)
CURLAUTH_ANYSAFE (integer)
CURLOPT_PROXYAUTH (integer)
CURLOPT_MAX_RECV_SPEED_LARGE (integer): Available since PHP 5.4.0 and cURL 7.15.5
CURLOPT_MAX_SEND_SPEED_LARGE (integer): Available since PHP 5.4.0 and cURL 7.15.5
CURLCLOSEPOLICY_LEAST_RECENTLY_USED (integer): Removed in PHP 5.6.0.
CURLCLOSEPOLICY_LEAST_TRAFFIC (integer): Removed in PHP 5.6.0.
CURLCLOSEPOLICY_SLOWEST (integer): Removed in PHP 5.6.0.
CURLCLOSEPOLICY_CALLBACK (integer): Removed in PHP 5.6.0.
CURLCLOSEPOLICY_OLDEST (integer): Removed in PHP 5.6.0.
CURLINFO_PRIVATE (integer): Available since PHP 5.2.4
CURLINFO_EFFECTIVE_URL (integer)
CURLINFO_HTTP_CODE (integer)
CURLINFO_HEADER_OUT (integer): Available since PHP 5.1.3
CURLINFO_HEADER_SIZE (integer)
CURLINFO_REQUEST_SIZE (integer)
CURLINFO_TOTAL_TIME (integer)
CURLINFO_NAMELOOKUP_TIME (integer)
CURLINFO_CONNECT_TIME (integer)
CURLINFO_PRETRANSFER_TIME (integer)
CURLINFO_SIZE_UPLOAD (integer)
CURLINFO_SIZE_DOWNLOAD (integer)
CURLINFO_SPEED_DOWNLOAD (integer)
CURLINFO_SPEED_UPLOAD (integer)
CURLINFO_FILETIME (integer)
CURLINFO_SSL_VERIFYRESULT (integer)
CURLINFO_CONTENT_LENGTH_DOWNLOAD (integer)
CURLINFO_CONTENT_LENGTH_UPLOAD (integer)
CURLINFO_STARTTRANSFER_TIME (integer)
CURLINFO_CONTENT_TYPE (integer)
CURLINFO_REDIRECT_TIME (integer)
CURLINFO_REDIRECT_COUNT (integer)
CURLINFO_REDIRECT_URL (string): Available since PHP 5.3.7
CURLINFO_PRIMARY_IP (string): Available since PHP 5.4.7
CURLINFO_PRIMARY_PORT (integer): Available since PHP 5.4.7
CURLINFO_LOCAL_IP (string): Available since PHP 5.4.7
CURLINFO_LOCAL_PORT (integer): Available since PHP 5.4.7
CURL_TIMECOND_IFMODSINCE (integer)
CURL_TIMECOND_IFUNMODSINCE (integer)
CURL_TIMECOND_LASTMOD (integer)
CURL_VERSION_IPV6 (integer)
CURL_VERSION_KERBEROS4 (integer)
CURL_VERSION_SSL (integer)
CURL_VERSION_LIBZ (integer)
CURLVERSION_NOW (integer)
CURLE_OK (integer)
CURLE_UNSUPPORTED_PROTOCOL (integer)
CURLE_FAILED_INIT (integer)
CURLE_URL_MALFORMAT (integer)
CURLE_URL_MALFORMAT_USER (integer)
CURLE_COULDNT_RESOLVE_PROXY (integer)
CURLE_COULDNT_RESOLVE_HOST (integer)
CURLE_COULDNT_CONNECT (integer)
CURLE_FTP_WEIRD_SERVER_REPLY (integer)
CURLE_FTP_ACCESS_DENIED (integer)
CURLE_FTP_USER_PASSWORD_INCORRECT (integer)
CURLE_FTP_WEIRD_PASS_REPLY (integer)
CURLE_FTP_WEIRD_USER_REPLY (integer)
CURLE_FTP_WEIRD_PASV_REPLY (integer)
CURLE_FTP_WEIRD_227_FORMAT (integer)
CURLE_FTP_CANT_GET_HOST (integer)
CURLE_FTP_CANT_RECONNECT (integer)
CURLE_FTP_COULDNT_SET_BINARY (integer)
CURLE_PARTIAL_FILE (integer)
CURLE_FTP_COULDNT_RETR_FILE (integer)
CURLE_FTP_WRITE_ERROR (integer)
CURLE_FTP_QUOTE_ERROR (integer)
CURLE_HTTP_NOT_FOUND (integer)
CURLE_WRITE_ERROR (integer)
CURLE_MALFORMAT_USER (integer)
CURLE_FTP_COULDNT_STOR_FILE (integer)
CURLE_READ_ERROR (integer)
CURLE_OUT_OF_MEMORY (integer)
CURLE_OPERATION_TIMEOUTED (integer)
CURLE_FTP_COULDNT_SET_ASCII (integer)
CURLE_FTP_PORT_FAILED (integer)
CURLE_FTP_COULDNT_USE_REST (integer)
CURLE_FTP_COULDNT_GET_SIZE (integer)
CURLE_HTTP_RANGE_ERROR (integer)
CURLE_HTTP_POST_ERROR (integer)
CURLE_SSL_CONNECT_ERROR (integer)
CURLE_FTP_BAD_DOWNLOAD_RESUME (integer)
CURLE_FILE_COULDNT_READ_FILE (integer)
CURLE_LDAP_CANNOT_BIND (integer)
CURLE_LDAP_SEARCH_FAILED (integer)
CURLE_LIBRARY_NOT_FOUND (integer)
CURLE_FUNCTION_NOT_FOUND (integer)
CURLE_ABORTED_BY_CALLBACK (integer)
CURLE_BAD_FUNCTION_ARGUMENT (integer)
CURLE_BAD_CALLING_ORDER (integer)
CURLE_HTTP_PORT_FAILED (integer)
CURLE_BAD_PASSWORD_ENTERED (integer)
CURLE_TOO_MANY_REDIRECTS (integer)
CURLE_UNKNOWN_TELNET_OPTION (integer)
CURLE_TELNET_OPTION_SYNTAX (integer)
CURLE_OBSOLETE (integer)
CURLE_SSL_PEER_CERTIFICATE (integer)
CURLE_GOT_NOTHING (integer)
CURLE_SSL_ENGINE_NOTFOUND (integer)
CURLE_SSL_ENGINE_SETFAILED (integer)
CURLE_SEND_ERROR (integer)
CURLE_RECV_ERROR (integer)
CURLE_SHARE_IN_USE (integer)
CURLE_SSL_CERTPROBLEM (integer)
CURLE_SSL_CIPHER (integer)
CURLE_SSL_CACERT (integer)
CURLE_BAD_CONTENT_ENCODING (integer)
CURLE_LDAP_INVALID_URL (integer)
CURLE_FILESIZE_EXCEEDED (integer)
CURLE_FTP_SSL_FAILED (integer)
CURLE_SSH (integer): Available since PHP 5.3.0 and cURL 7.16.1.
CURLFTPAUTH_DEFAULT (integer): Available since PHP 5.1.0
CURLFTPAUTH_SSL (integer): Available since PHP 5.1.0
CURLFTPAUTH_TLS (integer): Available since PHP 5.1.0
CURLPROXY_HTTP (integer): Available since cURL 7.10.
CURLPROXY_SOCKS4 (integer): Available since PHP 5.2.10 and cURL 7.10.
CURLPROXY_SOCKS5 (integer): Available since cURL 7.10.
CURL_NETRC_OPTIONAL (integer)
CURL_NETRC_IGNORED (integer)
CURL_NETRC_REQUIRED (integer)
CURL_HTTP_VERSION_NONE (integer)
CURL_HTTP_VERSION_1_0 (integer)
CURL_HTTP_VERSION_1_1 (integer)
CURLM_CALL_MULTI_PERFORM (integer)
CURLM_OK (integer)
CURLM_BAD_HANDLE (integer)
CURLM_BAD_EASY_HANDLE (integer)
CURLM_OUT_OF_MEMORY (integer)
CURLM_INTERNAL_ERROR (integer)
CURLMSG_DONE (integer)
CURLOPT_KEYPASSWD (integer)
CURLOPT_SSH_AUTH_TYPES (integer)
CURLOPT_SSH_HOST_PUBLIC_KEY_MD5 (integer)
CURLOPT_SSH_PRIVATE_KEYFILE (integer)
CURLOPT_SSH_PUBLIC_KEYFILE (integer)
CURLMOPT_PIPELINING (integer): Available since PHP 5.5.0 and cURL 7.16.0.
CURLMOPT_MAXCONNECTS (integer): Available since PHP 5.5.0 and cURL 7.16.3.
CURLSSH_AUTH_ANY (integer)
CURLSSH_AUTH_DEFAULT (integer)
CURLSSH_AUTH_HOST (integer)
CURLSSH_AUTH_KEYBOARD (integer)
CURLSSH_AUTH_NONE (integer)
CURLSSH_AUTH_PASSWORD (integer)
CURLSSH_AUTH_PUBLICKEY (integer)
CURL_WRAPPERS_ENABLED (integer): Defined if PHP was configured with --with-curlwrappers . Moved to PECL in PHP 5.5.0.
CURLPAUSE_ALL (integer): Available since PHP 5.5.0 and cURL 7.18.0.
CURLPAUSE_CONT (integer): Available since PHP 5.5.0 and cURL 7.18.0.
CURLPAUSE_RECV (integer): Available since PHP 5.5.0 and cURL 7.18.0.
CURLPAUSE_RECV_CONT (integer): Available since PHP 5.5.0 and cURL 7.18.0.
CURLPAUSE_SEND (integer): Available since PHP 5.5.0 and cURL 7.18.0.
CURLPAUSE_SEND_CONT (integer): Available since PHP 5.5.0 and cURL 7.18.0.
CURLPIPE_NOTHING (integer): Available since PHP 7.0.0 and cURL 7.43.0.
CURLPIPE_HTTP1 (integer): Available since PHP 7.0.0 and cURL 7.43.0.
CURLPIPE_MULTIPLEX (integer): Available since PHP 7.0.0 and cURL 7.43.0.
CURLPROXY_SOCKS4A (integer): Available since PHP 5.5.23 and PHP 5.6.7 and cURL 7.18.0.
CURLPROXY_SOCKS5_HOSTNAME (integer): Available since PHP 5.5.23 and PHP 5.6.7 and cURL 7.18.0.

User Contributed Notes

s dot coletta at unidata dot it

6 years ago


Beware of CURLE_* constants!

On the official site:

http://curl.haxx.se/libcurl/c/libcurl-errors.html

some constants are different, some missing compared to the PHP implementation.

Some examples:

in PHP the curl error number 28 is called

CURLE_OPERATION_TIMEOUTED

while in the official site is:

CURLE_OPERATION_TIMEDOUT

So if you use the second, it won't march the error 28 because in PHP it is not defined that way.

The same is for these:

CURLE_HTTP_RETURNED_ERROR
CURLE_UPLOAD_FAILED
CURLE_INTERFACE_FAILED
CURLE_SSL_CERTPROBLEM
CURLE_SEND_FAIL_REWIND
CURLE_LOGIN_DENIED
CURLE_AGAIN

that are in someway named differently or missing from PHP.

nimasdj [AT] yahoo [DOT] com

9 months ago


I hope this would be useful to convert error codes:

<?php
$curl_errno = array(
1  => "CURLE_UNSUPPORTED_PROTOCOL",
2  => "CURLE_FAILED_INIT",
3  => "CURLE_URL_MALFORMAT",
4  => "CURLE_URL_MALFORMAT_USER",
5  => "CURLE_COULDNT_RESOLVE_PROXY",
6  => "CURLE_COULDNT_RESOLVE_HOST",
7  => "CURLE_COULDNT_CONNECT",
8  => "CURLE_FTP_WEIRD_SERVER_REPLY",
9  => "CURLE_FTP_ACCESS_DENIED",
10 => "CURLE_FTP_USER_PASSWORD_INCORRECT",
11 => "CURLE_FTP_WEIRD_PASS_REPLY",
12 => "CURLE_FTP_WEIRD_USER_REPLY",
13 => "CURLE_FTP_WEIRD_PASV_REPLY",
14 => "CURLE_FTP_WEIRD_227_FORMAT",
15 => "CURLE_FTP_CANT_GET_HOST",
16 => "CURLE_FTP_CANT_RECONNECT",
17 => "CURLE_FTP_COULDNT_SET_BINARY",
18 => "CURLE_FTP_PARTIAL_FILE or CURLE_PARTIAL_FILE",
19 => "CURLE_FTP_COULDNT_RETR_FILE",
20 => "CURLE_FTP_WRITE_ERROR",
21 => "CURLE_FTP_QUOTE_ERROR",
22 => "CURLE_HTTP_NOT_FOUND or CURLE_HTTP_RETURNED_ERROR",
23 => "CURLE_WRITE_ERROR",
24 => "CURLE_MALFORMAT_USER",
25 => "CURLE_FTP_COULDNT_STOR_FILE",
26 => "CURLE_READ_ERROR",
27 => "CURLE_OUT_OF_MEMORY",
28 => "CURLE_OPERATION_TIMEDOUT or CURLE_OPERATION_TIMEOUTED",
29 => "CURLE_FTP_COULDNT_SET_ASCII",
30 => "CURLE_FTP_PORT_FAILED",
31 => "CURLE_FTP_COULDNT_USE_REST",
32 => "CURLE_FTP_COULDNT_GET_SIZE",
33 => "CURLE_HTTP_RANGE_ERROR",
34 => "CURLE_HTTP_POST_ERROR",
35 => "CURLE_SSL_CONNECT_ERROR",
36 => "CURLE_BAD_DOWNLOAD_RESUME or CURLE_FTP_BAD_DOWNLOAD_RESUME",
37 => "CURLE_FILE_COULDNT_READ_FILE",
38 => "CURLE_LDAP_CANNOT_BIND",
39 => "CURLE_LDAP_SEARCH_FAILED",
40 => "CURLE_LIBRARY_NOT_FOUND",
41 => "CURLE_FUNCTION_NOT_FOUND",
42 => "CURLE_ABORTED_BY_CALLBACK",
43 => "CURLE_BAD_FUNCTION_ARGUMENT",
44 => "CURLE_BAD_CALLING_ORDER",
45 => "CURLE_HTTP_PORT_FAILED",
46 => "CURLE_BAD_PASSWORD_ENTERED",
47 => "CURLE_TOO_MANY_REDIRECTS",
48 => "CURLE_UNKNOWN_TELNET_OPTION",
49 => "CURLE_TELNET_OPTION_SYNTAX",
50 => "CURLE_OBSOLETE",
51 => "CURLE_SSL_PEER_CERTIFICATE",
52 => "CURLE_GOT_NOTHING",
53 => "CURLE_SSL_ENGINE_NOTFOUND",
54 => "CURLE_SSL_ENGINE_SETFAILED",
55 => "CURLE_SEND_ERROR",
56 => "CURLE_RECV_ERROR",
57 => "CURLE_SHARE_IN_USE",
58 => "CURLE_SSL_CERTPROBLEM",
59 => "CURLE_SSL_CIPHER",
60 => "CURLE_SSL_CACERT",
61 => "CURLE_BAD_CONTENT_ENCODING",
62 => "CURLE_LDAP_INVALID_URL",
63 => "CURLE_FILESIZE_EXCEEDED",
64 => "CURLE_FTP_SSL_FAILED",
79 => "CURLE_SSH"
);
?>

Ron

8 years ago


<?

/*

* Author: Ron

* Released: August 4, 2007

* Description: An example of the disguise_curl() function in order to grab contents from a website while remaining fully camouflaged by using a fake user agent and fake headers.

*/



$url = 'http://www.ericgiguere.com/tools/http-header-viewer.html';



// disguises the curl using fake headers and a fake user agent.

function disguise_curl($url)

{

  $curl = curl_init();



  // Setup headers - I used the same headers from Firefox version 2.0.0.6

  // below was split up because php.net said the line was too long. :/

  $header[0] = "Accept: text/xml,application/xml,application/xhtml+xml,";

  $header[0] .= "text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5";

  $header[] = "Cache-Control: max-age=0";

  $header[] = "Connection: keep-alive";

  $header[] = "Keep-Alive: 300";

  $header[] = "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7";

  $header[] = "Accept-Language: en-us,en;q=0.5";

  $header[] = "Pragma: "; // browsers keep this blank.



  curl_setopt($curl, CURLOPT_URL, $url);

  curl_setopt($curl, CURLOPT_USERAGENT, 'Googlebot/2.1 (+http://www.google.com/bot.html)');

  curl_setopt($curl, CURLOPT_HTTPHEADER, $header);

  curl_setopt($curl, CURLOPT_REFERER, 'http://www.google.com');

  curl_setopt($curl, CURLOPT_ENCODING, 'gzip,deflate');

  curl_setopt($curl, CURLOPT_AUTOREFERER, true);

  curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);

  curl_setopt($curl, CURLOPT_TIMEOUT, 10);



  $html = curl_exec($curl); // execute the curl command

  curl_close($curl); // close the connection



  return $html; // and finally, return $html

}



// uses the function and displays the text off the website

$text = disguise_curl($url);

echo $text;

?>



~Ron

me at ruslanbes dot com

11 months ago


Note that prior to PHP 5.5 following constants were missing and were available only through their numeric values:

CURL_SSLVERSION_DEFAULT // 0
CURL_SSLVERSION_TLSv1  // 1
CURL_SSLVERSION_SSLv2 // 2
CURL_SSLVERSION_SSLv3 // 3

This was fixed after this support request: https://bugs.php.net/bug.php?id=62318

uramihsayibok, gmail, com

7 months ago


Regarding CURLE_OPERATION_TIMEDOUT vs. CURLE_OPERATION_TIMEOUTED:

Originally cURL had the constant named TIMEOUTED (read: "timeout-ed"). This was changed[1] in 2007 and v7.17.0 to be TIMEDOUT (read: "timed out") and the old constant kept in place as an alias.

PHP started off using TIMEOUTED as well. The TIMEDOUT constant was added[2] in 2012 and v5.5.0 and the old constant was *kept in place*.

If you ask me, the TIMEDOUT constant reads more nicely (not to mention is technically the correct one to use) and as long as you're using PHP 5.5+ then it is available. If you have to support older versions then I suggest you keep using the new constant and add a polyfill like

<?php
if (version_compare(PHP_VERSION, "5.5.0", "<")) {
    define("CURLE_OPERATION_TIMEDOUT", CURLE_OPERATION_TIMEOUTED);
}
?>

or

<?php
// PHP <5.5.0
defined("CURLE_OPERATION_TIMEDOUT") || define("CURLE_OPERATION_TIMEDOUT", CURLE_OPERATION_TIMEOUTED);
?>

to be removed once you stop supporting them.

[1] https://github.com/bagder/curl/commit/9f44a95522162c0f4a61093efe1bf1f58b087358#diff-d8c6cb80505e0f7d5e27fca2a682aa34L119
[2] https://github.com/php/php-src/commit/9ab45d3edbafa3ee751472c3f8d1fb3f51f38cf1#diff-ac978e3de205f1d14eb960e0eb15ef24R723